Motor vehicle air spring system having an ultrasonic measurement arrangement

Abstract

An air spring system for a motor vehicle includes essentially a flexible member ( 4 ) having first and second ends. At a first end, the flexible member is closed off by the cover plate ( 8 ) as a connecting part and, at its second end, by a roll-off piston ( 10 ) as a second connecting part. To carry out a contactless distance measurement in accordance with the pulse/echo method in the interior space ( 6 ) of the air spring ( 2 ), an ultrasonic transmitter/receiver ( 14 ) is mounted on one of the two connecting parts ( 8, 10 ) and a reflector ( 16 ) is provided on the other one of the two connecting parts ( 8, 10 ). A separate reference reflector ( 18 ) is not used in order to simplify the construction and to save mounting space for the components. Instead, the reflector is configured as a two-step reflector. The one step functions as a target reflector ( 16 ) and the other step ( 26 ) functions as a reference reflector. A bumper ( 28 ) is preferably configured as a two-step target reflector ( 16 ). The step, which is configured in the bumper ( 28 ) is realized as a blind bore ( 20 ).

What is claimed is:  
     
       1. An air spring system for a motor vehicle, the air spring system comprising: 
       a first connecting part defining a cover plate;  
       a second connecting part defining a roll-off piston;  
       said first and second connecting parts being disposed at a spacing from each other which rapidly changes with the movement of said motor vehicle over a road surface;  
       a flexible member having a first end connected to said first connecting part and a second and connected to said second connecting part;  
       an ultrasonic arrangement for making contactless measurements of the distance between said first and second connecting parts;  
       said ultrasonic arrangement including an ultrasonic transmitter/receiver mounted on one of said connecting parts and a reflector mounted on the other one of said connecting parts;  
       said reflector being configured as a two-step reflector having first and second steps; and,  
       one of said steps being a target reflector and the other one of said steps being a reference reflector and both of said reflectors being at respective distances from said ultrasonic transmitter/receiver which likewise rapidly change as said spacing changes.  
     
     
       2. The air spring of  claim 1 , wherein said cover plate, said roll-off piston and said flexible member conjointly define an air spring having an air spring interior; and, said air spring system further comprises a bumper mounted on one of said cover plate and said roll-off piston so as to face toward said interior of said air spring; and, said bumper is configured as said two-step reflector. 
     
     
       3. The air spring of  claim 2 , wherein said ultrasonic transmitter/receiver is mounted on said cover plate so as to face toward said interior; and, said two-step reflector is mounted on said roll-off piston so as to face toward said interior. 
     
     
       4. The air spring of  claim 2 , wherein the step of said two-step reflector is defined by a central blind bore formed in said bumper. 
     
     
       5. The air spring of  claim 4 , wherein said central blind bore has a diameter of 12 mm and a depth of 7.5 mm.